The present invention relates to a device for preventing a bolt from slipping out of a bore for inserting the shank of the bolt even when the externally threaded portion of the bolt is disengaged from an internally threaded portion.
In fluid control apparatus, for example, for use in manufacturing semiconductors, coupling members are fixed to a base plate with bolts, and on-off valves are each fixed to one or some of the coupling members with bolts. These bolts are not always screwed in from above; some are often screwed in laterally or from below.
The conventional fluid control apparatus has the problem that in the case where the base plate is vertical, the bolt is likely to slip out of a bolt shank bore when the externally threaded portion of the bolt is disengaged from an internally threaded portion.